Q & A: Human Skin

Learn more physics!

Related Questions

Still Curious?Explore Q&As in related categories

What atoms or molecules make up the human skin? - Jimmy Chantler (age 12)Rod Kelley, Gilroy,CA,U.S.A

A:

Jimmy -

Whoa! This is actually a way more complicated question than you
probably expected. But I'll give it a shot anyways. The human (and
other mammals) the skin has two layers, the dermis and the epidermis.
The dermis is the layer on the inside and contains blood vessels,
nerves, hair follicles, small muscles, sweat glands, and all sorts of
other things. The chemical make-up of these things is very complicated.

The epidermis is the outside layer and is made up of the skin cells
that you're used to thinking about. These are some of the simplest
cells in the body, but they're still pretty complicated. Since it would
take me a /really/ long time to talk about all of the different atoms
and molecules in the dermis, I'll just talk about the regular skin
cells (even though all of those other things are technically still part
of the "skin"). The most common molecule the human body (and the skin)
is water (H2O). Water makes up about 50-70% of the body's total weight.

Other than water, there are 4 types of molecules that scientists
call organic molecules. This is what almost all of the human body is
made up of. (But there are some inorganic molecules in the body, too.)

The first of these types of molecules is the carbohydrates.
Carbohydrates are molecules that are made up of Hydrogen, Carbon, and
Oxygen atoms only. These are sugars and are used by the cells as a
source of energy. The most common carbohydrate in the body is glucose
(C6H12O6), and the cells use this to make a special molecule called ATP
(adenosine triphosphate), which also contains phosphorus atoms. (ATP is
the molecule that actually provides energy inside the cell.) Some other
examples of carbohydrates are glycogen, sucrose, and fructose.

The next type of molecule is called a lipid. Lipids are also made
of Hydrogen, Carbon, and Oxygen atoms, but they also sometimes contain
Phosphorus and/or Nitrogen.) These are fats and are used by cells for a
number of different things. Most of the skin cells on the very outside
of your skin are actually dead, so the most important thing that these
molecules do is to hold them together. This may sound wierd, but if
you've ever mixed oil (a lipid) with water, you know that they don't
mix at all. So these molecules are used to make the "membrane" of the
cell, which is the part that goes around the outside of the cell. This
"phospholipid bilayer" holds the water inside the cell. (It's called a
"bilayer" because there's actually two layers of it, and it's
"phospholipid" because it's actually a somewhat more complicated
molecule than just a lipid.)

The next type of molecule is proteins. Proteins contain Hydrogen,
Carbon, Oxygen, Nitrogen, and usually Sulfur atoms. Most of the things
in cells that "do stuff" are proteins. These are things like hormones
and enzymes and all sorts of other things. One common protein in skin
cells is called keratin. Keratin is a large, complicated molecule that
makes cells stronger. This is important for skin cells, because they
rub up against things a lot.

The last major type of organic molecule is nucleic acids. These
contain Hydrogen, Carbon, Oxygen, Nitrogen, and Phosphorus atoms. These
are the molecules that make up DNA (deoxyribonucleic acid). (They also
make up RNA.) DNA is the most important part of any cell, because it
contains the information that determines what your body is. For
example, your DNA determines whether you'll have blue eyes or brown
eyes and whether you'll be tall or short. It also tells your body to
have two arms, two legs, etc. The four nucleic acids that make up DNA
are called cytosine, guanine, thymine, and adenine. The DNA molecule
also contains the sugar deoxyribose (a carbohydrate), which holds it
all together.

These are only a few of the different molecules that make up the
skin. In fact, there's more different molecules in just the skin than I
can count! (And there's a whole lot of them that we don't even know
about yet!)

This is a list that I found of the most common elements (atoms) in
the human body and how much of them there are (I couldn't find a list
for just the skin):